Over the years many apparatus and methods have been developed for joining ends of flexible, strip like materials such as paper, plastic films, metal foils, photographic film strips and the like, which are collectively referred to in this specification as webs of material. The ends of such webs have been joined by overlapped joints with glue or thermal fusion and by butt joints with tape, for example. The apparatus and methods used have been manual, automatic and combinations of the two and have enjoyed widely varying degrees of success.
For example, U.S. Pat. No. 3,245,861 discloses a web splicer for use in label printing equipment in which the lead end of the following or new length of web is manually trimmed and a length of tape is applied across the trimmed end. The preceding or old length of web is then stopped as its source spool is emptied and its tail end is trimmed. The new lead end and applied strip of tape are then pressed against the old tail end to form an overlapping joint. Such overlapping joints are acceptable in many industrial applications but present problems during subsequent handling of the web in other applications. U.S. Pat. No. 3,939,032 discloses a web butt splicer in which the new lead end is trimmed manually and a length of tape is applied across the lead end. The old tail end is then trimmed at the same location and the two trimmed ends are pressed together to form a butt joint. U.S. Pat. No. 4,234,365 shows a web butt joining system in which the old web and the new web are threaded between a pair of cutting wheels which trim their ends and convey the two ends in abutment to a pair of tape applicator wheels which place strips of tape on both sides of the butt joint.
U.S. Pat. No. 4,501,630 discloses an apparatus for splicing a leader to magnetic tape in which the leader and tape are fed along parallel, coplanar guide grooves in a receiving table which is movable transversely to permit either the leader or the tape to move into a coplanar guide groove on an adjacent receiving table. After the lead end of the tape and the tail end of the leader have been trimmed in separate operations, the two ends are abutted and a strip of tape is applied. U.S. Pat. No. 4,629,531 shows an apparatus for joining sheet ends such as might be used in a newspaper printing plant. The new web is stopped and trimmed manually, after which glue is applied to its lead end. Then the old web is stopped and trimmed, after which the lead end of the new web is overlapped with the tail end of the old web. U.S. Pat. No. 4,801,342 discloses a method and an apparatus for forming a butt splice in which the old web and the new web are run along opposite sides of a planar cutting anvil along whose edge cutting wheels are run to trim the lead and tail ends, after which a strip of tape is rolled over the abutted ends.
Splicers of the types shown in these patents typically require intervention by the operator for steps such as trimming the lead or tail ends or applying tape strips to applicator wheels or to the trimmed ends. While this type of operator involvement is acceptable in many applications, certain high speed web handling operations, such as the spooling of photographic film, are slowed undesirably. Particularly when the web handling must take place in the dark, as in photographic applications, the operator's involvement can significantly slow the process.
A variety of tape applicator devices also have been used in splicers of the general sort just described. For example, U.S. Pat. No. 4,328,066 shows a tape splicer in which the tape is pulled onto a rotating vacuum drum which is translated into contact with the abutted ends to complete the splice, after which the vacuum drum is withdrawn to a position where the next strip can be cut. A separate roller is used to smooth out the splice. U.S. Pat. Nos. 4,475,970 and 4,478,674 show tape splicers in which the tape is cut to lengths on a square block and then press applied to the abutted ends. More recently, U.S. Pat. No. 4,848,691 shows a splicer in which the new web is trimmed, a strip of tape is applied to its trimmed end and then the trimmed end and tape are pressed into a lap joint with the still moving old web.
Other types of tape dispensers also have been used extensively. One type, manufactured by the 3M Company, uses knurled disks to move the tape through the dispenser. The operator depresses a ratcheting crank which turns the knurled disks to meter the tape, after which the operator must cut the tape against an adjacent serrated blade. Another type of dispenser, also made by the 3M Company, meters and cuts the tape by means of a metering wheel whose periphery comprises a series of raised ribs which contact the sticky side of the tape. Between these ribs are recesses large enough to permit the operator to insert a finger to peel away a cut strip after a plunge type knife has severed the tape near the preceding rib. In still another type of dispenser, the free end of a tape is pushed through the throat of a guillotine type cutter, which can lead to stubbing of the tape and improper operation of the dispenser.